Automatic heat requirement regulator for automatic change-over system for blast stoves for blast furnaces



3,051,465 HANGE-ovER Aug 28, 1962 H. JANSEN ETAL AUTOMATIC HEAT REQUIREMENT REGULATOR FOR AUTOMATIC C SYSTEM FOR BLAST STOVES FOR BLAST FURNACES Filed Nov. 16, 1959 5 Sheets-Sheet 1 Aug. 28, 1962 H. JANSEN ETAL 3,051,465

AUTOMATIC HEAT REQUIREMENT REGULATOR FOR AUTOMATIC CHANGE-OVER sYsTEM FOR BLAST sTOvEs FOR BLAST FURNAcEs Enea Nov. 1e, 1959 5 sheets-sheet 2 Aug. 28, 1962 H. JANSEN E-rAL 3,051,465 HANGE-ovER sT sTovEs FOR BLAST FURNACES AUTOMATIC HEAT REQUIREMENT REGULATOR FOR AUTOMATIC C SYSTEM FOR BLA Filed NOV. 16, 1959 5 Sheets-Sheet 5 ATTORNEY H. JANSEN ET AL 3,051,465 AUTOMATIC HEAT REQUIREMENT REGULATOR FOR AUTOMATIC CHANGE-OVER SYSTEM FOR BLAST STOVES FOR BLAST FURNACES Filed NOV. 1.6, 1959 5 Sheets-Sheet 4 5 m a To@ E Q Q v4 J *MQ WM o o m. am, R R R R T EFS @OAS @AS GAS en w Rm W w S 5% S S SE SSI S QN QE QN QN 5% S /E NSN N- N v m m m Nm mi NQ n wk S \w TSS w .S S 5% EN R l ,i

u u ESSE E N kmxu Aug. 28, 1962 AUTOMATIC HEAT REQUIREMENT REGULATOR FOR AUTOMATIC CHANGE-OVER SYSTEM FOR BLAST STOVES FOR BLAST FURNACES Filed NOV. 16, 1959 H. JANSEN ET Al.

5 Sheets-Sheet 5 assigns tice 3,051,465 AUTOMATIC HEAT REQUEREMENT REGULATR FOR AUTMATHC CHANGE-@VER SYSTEM FR BLAST STOVES FOR BLAST FURNACES Hermann Jansen and Ludwig Walther, Dnren, Rhineland,

Germany, assignors to Zimmermann c Jansen Gesellschaft mit beschrankter Haftung, Duren, Rhineland, Germany, a corporation of Germany Filed Nov. 16, 1959, Ser. No. 853,357 Claims priority, application Germany July 16, 1959 S Claims. (Cl. 263-19) The present invention relates to an .automatic heat requirement regulator for a Vblast furnace installation which is provided with three blast stoves for supplying a continuous stream of hot blast to the blast furnace.

In a three-stove system for a blast furnace, it is desirable to have one stove in On Blast condition, while the other two stoves are in On Gas condition. Under this kind of arrangement, the heat requirement for the blast furnace is at all times furnished by two of the three hot blast stoves which share such requirement equally. In such a three-stove system for a blast furnace, it is also possible to remove one of the stoves from operation leaving the remaining two stoves to alternately go On Blast and On Gas in order to supply a continuous stream of hot blast to the blast furnace. Under this kind of arrangement, namely a two-stove arrangement, one stove is at all times supplying the entire heat requirement for the blast furnace.

' According to the present invention, there is provided heat requirement regulator means for automatically adjusting the heat requirement for the respective stoves, when they are On Gas, whether one or two stoves are supplying the entire heat requirement to the blast furnace.

According to another aspect of the invention, there is provided heat requirement regulator means which may be manually set when any of the stoves in the multi-stove system is operated manually and independently of the others.

It is, therefore, an object of the present invention to provide heat requirement regulator means for automatically controlling the required amount of heat to be furnished by one or more of the hot blast stoves in a blast furnace installation.

Another object of the present invention is to provide automatic heat requirement regulator means for a threestove blast furnace installation which is arranged to automatically distribute the heat requirement equally between two of the three stoves when the installation is operating with all three stoves, in automatic fashion.

Another object of the present invention is the provision for automatically causing a stove that is n Gas to produce its maximum output, when said stove is operating .automatically with only one of the other two stoves in the system, while the third stove is taken out of automatic operation.

The above and other objects, features and advantages of the present invention will be more fully understood from the following description considered in connection with the accompanying illustrative drawings.

In the drawings:

FIG. 1 is a schematic layout of a blast furnace installation utilizing three hot blast stoves, for which is provided the automatic heat requirement regulating means in accordance with the invention;

FIG. 2 represents the total circuitry associated with the automatic heat requirement regulation of the threestove system, in accordance with the invention;

FIG. 3 is a schematic circuit diagram of the circuitryv FIG. 4 is a circuit diagram similar to FIG. 3, but showing the condition of the circuit when stoves I and II are being operated automatically, while stove III is taken out of automatic operation; and

FIG. 5 is a circuit diagram similar to FIGS. 3 and 4, but showing the condition of the circuit when all three stoves are operated manually, one independently of the other.

Referring now to the drawings in detail, FIG. 1 shows a diagrammatic or schematic layout illustrating an arrangement for a blast furnace served by three hot blast stoves, namely stove I, stove II and stove III. It will be understood that the Roman numerals I, II and III which identify the respective stoves are also used to identify the various valves, elements, components, relays, etc., associated with stove I, stove ll and stove III, respectively. As is indicated above, the hot blast stoves serve to provide a continuous hot blast required for the blast furnace operation. In a multiple stove system, it is necessary to have, at all times during which the blast furnace is expected to operate, at least one of the stoves On Blast. Accordingly, at least one of the hot blast stoves is .at all times in direct communication, by means of the hot blast main 10, with the blast furnace, while one or both of the other hot blast stoves are being heated up by the combustion of blast furnace gas.

Each hot blast stove is provided with a burner, generally indicated by the reference numeral 12, which has a flame for igniting the gas-air mixture. Burner 12 is connected via a connecting pipe 14 to the gas main 16. In the connecting pipe 14 to each burner there is provided a gas regulating butterfly valve GRBV to control the gas How. Each burner is provided with a conventional gas shut-off valve GV and a conventional burner shut-olf valve BV. As is well known to those skilled in the art, the gas shut-ntf valve functions to isolate the burner from the gas main and the burner shut-off Valve functions to isolate the burner from a hot blast stove. Each stove is provided with a fan 18, which supplies the air required for combustion of the gas, through a conventional combustion air ybutterfly valve CABV. The CABV valve is positioned in combustion air conduit 20 which extends between the fan l and the burner 12.

The gas-air mixture is consumed in the combustion chamber 22 of each hot blast stove and the resultant hot ilue gases heat up the checker work 24 in each of the hot *blast stoves. After ilowing past the checker work 24, the

cooled ilue gases leave the stove through a conventional' chimney valve CV which functions to isolate the hot blast stove from the flue 26. One or two chimney valves may ybe provided for each hot blast stove, only one chimney valve being illustrated in FIG. 1. The cooled ue gases flow from the chimney valve through the flue 26 to a stack which is not illustrated.

A conventional cold blast valve CBV is provided for each stove and is connected to a cold blast main 28 and functions to isolate the hot blast stove from the cold blast main. The cold blast main extends into a mixing main 30 which is connected to the hot blast main 10 via a mixing device M, the mixing device functioning to mix hot Iblast and cold lblast prior to its introduction into the bustle pipe BP of the blast furnace. Each stove is connected to the hot =blast main 10 yby means of a hot blast valve HBV, the hot blast main being provided with an extension pipe 32 for this purpose for each of the stoves. The hot blast main lll is provided with a pipe 34 which communicates with the -bustle pipe BP of the blast furnace.

`In FIG. l, stove I is shown, for purposes of illustration, in On Blast condition and stove II is shown in On Gas condition, and the ow lines for the fluids passing through each of these stoves are indicated in broken lines. For example, in the case of stove I, which is On Blast, there Patented Aug. 28, 1962 is a flow of air from the cold blast main 2S through the cold blast main 28 through the open cold blast valve CBV-I, through the stove and over the checker Work 24 therein, through the open associated hot blast valve HBV-I, through extension pipe 32 and through the het blast main and the mixing device M into the bustle pipe BP of the blast furnace BF.

In stove II, which is shown in FIG. 1 as being in On Gas condition, there is a ilow of gas from the gas main 16 through connecting pipe 14, through the open gas shutoff valve GV-II into the associated burner 12 where it is ignited, through the open burner shut-oif valve BV-II, and into the stove. At the same time, there is a flow of combustion air fed from associated fan 18 through the associated air conduit 20 into the burner, for mixture with the gas, the gas-air mixture being burned in the associated combustion chamber ZZ of the stove. The resultant flue gases pass from the checker work 24 of the stove into the stack via the open chimney valve CV-II.

`It is thus seen that when stove I is in On Blast condition, the gas shut-oif valve GV-l, the burner shut-off valve BV-I and the chimney valve CV-I are closed while the cold `blast valve CBV-I and the hot blast valve HBV-I are open to permit the total blast coming from the cold blast main 28 to be heated as it ilows past the checker work 24 of the stove, and into the bustle pipe BP of the blast furnace by way of the mixing device M.

With respect to stove II, which is shown in On Gas condition, it Awill be noted that the condition of its respective valves is exactly opposite so that the corresponding valves in stove I which is in On Blast condition. More specifically, in stove II, the cold blast valve CBV-II and the hot blast valve HBV-II are closed, while the gasshut-oif Valve GV-II, the burner shut-oit valve BV-II and the chimney valve CV-II are open, so as to provide an unimpeded flow into the stove of a combustibble air-gas mixture, as well as to provide an unimpeded iiow of the consumed mixture or iiue gases from the stove to the stack.k

In addition to the On Blast condition, as just described in connection with stove I, and the On Gas condition, just described in connection with stove II, there is another condition in which a stove may be, depending on the manner of operation of the three stoves, as will hereinafter be described in great detail. Such other condition is the On Bottled condition. In such condition of a stove all of its valves are closed, namely the gas valve, the burner valve, the hot blast valve, the cold blast valve and the chimney valve. A stove may be in such a condition either (l) when it is completely taken out of operation, or (2) when it has been On Gas for a long enough period of time so that its checker work is sufficiently hot and need not be additionally heated, at which time all its valves are closed and such a stove is kept in heated On Bottled condition until it is time for it to be placed On Blast.

`It is therefore seen that a stove can be in either one of three conditions, namely the On Gas condition, the "vOn Blast condition, or the On Bottled condition. For each of these conditions the valves of the stoves must be in their position described above. In order to place a stove in the On Blast condition from the On Gas condition, its valves are operatedk in the following sequence:

(l) The gas shut-off valve is closed; (2) The burner shut-off valve is closed; ('3 The chimney valve is closed;

(4,) 'Ille cold lblast valve is open; and (5) The hot blast valve is open.

In order to place a stove in the On Gas condition from the, On Blast condition, its valves are operated in the following sequence:

(l) The hot blast valve is closed; (2) The cold blast valve is closed; (3) The chimney valve is open;

(4) The burner shut-off valve is open; and (5) The gas shut-off valve is open.

In order to place a stove in the On Bottled condition, from the On Gas condition, its valves are operated in the following sequence:

(1) The gas shut-ott valve is closed; (2) The burner shut-off valve is closed; and (3) The chimney valve is closed.

An apparatus for the automatic sequential operation of the valves of the stoves, as described above, is shown and described in United States patent appln. Serial. No. 682,913, tiled September 9, 1957, now Patent No. 2,931,- 635, and assigned to the assignee of the present application.

In connection with the foregoing description it will be understood that the gas regulating butterfly valve GRBV controls the volume of the gas which enters the hot blast stove. This makes it possible, by means of a gas volume control, to predetermine the number of calories tot be stored in the checker work of each hot blast stove and, by controlling the combustion air volume via the combustion air butterfly valve CABV, to provide a gas-air ratio necessary for good combustion. Since the hot blast ilowing from a stove which is On Blast has a gradually decreasing temperature during the blast period, it is necessary, in order to keep the hot blast temperature in the bustle pipe BP of the blast furnace constant, to mix cold blast with the hot blast flowing frame the stove before reaching the bustle pipe ofthe blast furnace. This is done in previously `discussed mixer M, which is -fully shown and `described in United States patent application Serial No. 651,603, led April 9, 1957, and assigned to the assignee hereof.

For example, immediately after a stove is put On Blast the hot blast temperature exiting yfrom the stove may be at a temperature of about 1050" C. and may fall during the blast period down to 900 C. If the required temperature of the hot blast in the bustle pipe of the blast furnace is 900 C. then a greater cold blast volume must be mixed with the Ahot blast at the beginning of the blast period so that the resulting temperature of 900 C. is obtained in the bustle pipe. As the temperature of the hot blast `drops during the blast period, less cold blast is mixed with the hot blast in order tol maintain the required temperature in the bustle pipe, until the end of the, blast period at which time little or no cold blast is required.

As was stated before, the supply of cold blast to the hot blast main, before the entry of the -hot blast into the blast furnace, is effected `through the previously mentioned mixing main 30 located between the cold blast main 28 and the pipe 34 extending from the hot blast main 10. The volume of the cold blast is controlled by a conventional mixed blast butterily Valve MBBVS built into the mixing main 30, as indicated in FIG. 1. A system for initiating a change-over of another stove which is in On Gas condition to On Blast condition in a fully automatic manner when valve MBBVS closes at the end of the blast period for a particular stove is `fully disclosed in applicants co-pending application Serial No. 852,370, filed on the 12th `day of November 1959, assigned to the assignee hereof, now United States Patent No. 3,034,775, issued on May 15, 1962.

In a three-stove system, as shown in FIG. 1, it is desirable to have one stove in On Blast condition, while the other two stoves are in On Gas condition. When the stove that is On Blast has operated for its full cycle, one of the other stoves that was On Gas is placed in On Blast, the stove which was On Blast is placed On Gas and the other stove which was LOn Gas remains On Gas for a second cycle. In this way, a stove is On Gas for two cycles and On Blast for one cycle. In this connection, it is obvious that the stove which has been On Gas for the longest period of time, is the one which is selected to go On Blast in the next succeeding cycle. A system for eifectuating this change-over in a fully automatic manner, and for automatically selecting the stove which has been On Gas for the longest period of time to go On Blast is fully disclosed in said applicants co-pending application Serial No. 852,370, now United States Patent No. 3,034,775.

When the blast furnace installation is operated with the three stoves in fully automatic operation, it is clear that the heat for the blast -furnace is supplied by two of the three stoves at all times.

In accordance with the fully automatic system described in co-pending application Serial No. 852,370-, now United States Patent No. 3,034,775, the blast furnace installation can also be operated fully automatically with only two of the three stoves in the system, while the third stove is taken out of operation entirely. Under this kind of arrangement, one of the two stoves is On Gas While the other is On Blast. When the stove that is On Blast is at the end of its cycle, the stove that is On Gas is placed in the On Blast condition while the one that is On Blast is now placed On Gas. It is therefore apparent that when lthe system operates with only two stoves, one stove has to supply the required heat for the entire system, as compared to the three-stove system in which two stoves share in the heat requirements for the blast furnace.

As also set forth in applicants co-pending application Serial No. 852,370, now United States Patent No. 3,034,- 775, the circuitry associated with the three-stove installation, in addition to being adapted for operation with three stoves and two stoves, is also adapted for permitting each of [the stoves to be operated manually and independently of the other stoves.

For each of the three arrangements above, namely:

(l) Three-stove fully automatic operation; (2) Two-stove lfully automatic operation; and (3) Single stove manual operation,

there is provided, according to the present invention, a system for automatically adjusting the heat requirement for each stove, as will now be described.

Each stove is provided with a drive unit shown schematically in FIGS. 2 through 5 and identified by the reference characters DU-I, DU-II, and DU-III for stoves, I, II and III, respectively. Each drive unit is operative, in response to a signal fed into it, to control the extent to which the necessary valves are opened for the purpose of controlling the amount of gas volume allowed to enter the associated stove. Each drive unit DU has two incoming terminals V and M, respectively. A signal entering the drive unit DU through terminal V will produce an output from the drive unit proportional to the amplitude of said signal. Accordingly, the larger the signal fed into the drive unit through terminal V, the more gas volume will be permitted to be admitted in the associated stove. A signal coming through terminal M is automatically op. erative to cause the drive unit to allow the necessary valves to be opened to the maximum extent for correspondingly permitting a predetermined maximum amount of `gas volume to be admitted into the associated stove. llt is, of course, understood that the amount of heat produced by a stove is proportional to the amount of gas volume burned therein.

Generally speaking, the heat requirement of the blast blown through the blast furnace is a function of the following factors:

(l) The volume of the blast;

(2) The temperature of the blast; and

(3) A constant which depends on (a) the heat value of the fuel (B.t.u. per cubic foot, (b) the specic heat of Vthe yblast (B.t.u. per degree Fahrenheit per cubic foot),

and (c) the efficiency of the system.

The first two of these factors, namely the volume and .temperature of the blast, are determined by the particular output in steel production desired from the blast furnace. Accordingly, after such furnace output is decided upon, it is merely `a matter of mathematics to determine what the volume and temperature of the hot blast should be. The third of these factors is a constant which can easily be determined, depending upon the fuel used and the efficiency of the system.

All the above recited factors which determine the heat requirement are utilized to calculate the amount of volume of gas to be fed to the hot blast stove when they are being heated. As shown in FIGS. 2 through 5, there is provided a conventional computer in which are fed the various factors set forth above and out of which comes a single electrical signal, the amplitude of which is proportional to the gas volume requirement when such requirement is to be supplied by two stoves, that is, during the three-stove fully automatic operation. The output of the computer is fed into three amplifiers, namely AMPL-I, AMPL-II and AMPL-III, associated with stoves I, II and III, respectively. A conventional computer has been set forth herein as the device by which a single electric signal, the amplitude of which is proportinal to the gas volume requirement, is obtained. This computer is but one illustration of how such output signal is obtained, there being other conventional ways of obtaining said signal. 'Ihe invention herein relates primarily to the manner in which such output signal, no matter how obtained, is distributed to the three stoves to accomplish a desired result, and the particular means which produce such output signal, whether such means be a computer or something else, does not form part of this invention.

Each stove is provided with an A/M (automatic/manual) switch which is a manually operated two-way drum type switch. The respective switches A/MI, A/ MII and A/ MIII for stoves I, II and III are best shown in FIG. 2. Each of the A/ M switches operates a plurality of different sets of contacts, namely, contacts 10i-111, 3102-412, 10.3-113, 10ft-114, 105-1I5, 1106-116 and 107-117. These contacts are shown in FIG. 2 in their position when the A/M switches are set for fully automatic operation for each of the respective stoves, and in such position it will -be noted that contacts 10i-lll, IGZ-112, 10S-113 and 10S-115 are closed while contacts 1434-414, 106-116 `and 107-1317 are open. It will be understood that in the other position of the A/M switches, namely the position thereof for manual operation, the contacts shown open in FIG. 2 will be closed and vice versa.

Each stove is also provided with an interlocking relay for the gas condition (IR-G) which is automatically energized when ythe associated stove is in the On Gas condition, as fully set forth in applicants co-pending application Serial No. 852,370, now United States Patent No. 3,034,775. Each IR-G relay controls a pair of sets of contacts. For example, interlocking relay IR-GI controls contacts 10-20 and contacts 30SL The relays IR-G are shown in FIG. 2 in the de-energized condition thereof in which its sets of contacts are shown to be open.

There is provided for each stove a manual setter MS which is manually operated to control the amount of current passing therethrough. FIG. 2 represents all the circuitry associated with the automatic heat requirement regulation for the automatic three-stove system, the solid lines being used to represent the circuitry associated with the automatic heat requirement regulation of stove I, the dotted lines for that associated with stove II and the dot and `dash lines with that associated with stove III.

Referring now to FIG. 3, there is shown a schematic circuit diagram of the identical circuitry as that shown in FIG. 2, but arranged differently for the purpose of more clearly understanding the operation of the automatic heat requirement regulator. As shown, FIG. 3 is divided into three identical divisions associated with stoves I, II, and III, respectively. FIG. 3 shows the condition of the circuitry when all three stoves are set for fully automatic threestove operation and stoves I and Ii are On Gas. Under those conditions, all of the A/M switches are in their automatic position and the contacts thereof are exactly as shown in FIG. 2. Also, under these conditions, relays IR-GI and IR-GII are energized (because stoves I and II are shown On'Gas) and contacts itl-20 and 30-31 thereof are closed. It is now noted that a circuit is cornpleted, for stove l, from the computer, through AMPL-I, through contacts 101-111 of A/MII, through contacts 102-112 of A/ MIII, through contacts 103-113 of A/ MI, through contacts itl-Z of IR-GI, whereby the output of amplifier I is fed into the drive unit DU-I through terminal V. This automatically causes the drive unit DU-I to be operative to permit the opening of the gas regulating butteriiy valve GRBV of stove I Van amount proportional to the amplitude to the signal coming from the computer so as to automatically cause stove I to supply the required amount of heat. A similar `circuit is completed for stove Il from the computer to DUII for automatically causing stove II to supply the required amount of heat. At the same time that stoves I and Il are On Gas and automatically burning the required amount of gas dictated by the computer, the drive unit DU-III of stove III is inoperative because relay IR-GIII is de-energized. This is, of course, desirable, since stove Ill is not in the On Gas condition.

FIG. 4 is similar to FIG. 3 but represents the condition of the system when stoves I and II are set for automatic two-stove operation and stove I is On Gas, while stove III is taken entirely :out of operation. Under these conditions, switch A/ MI and switch A/ MII are in the automatic position, while switch A/MIII is in the manual position. It is now seen that the circuit through which DUeI received its signal in stove I in FIG. 3 is now open because contacts 1012-112 of A/MIII are open. On the other hand, it is noted that there is a complete circuit to drive unit DU-I from line LI, through contacts 104-114 of A/MIII (which are now closed), through contacts S-115 of A/ MI and through contacts Sti-31 of IR-GI into terminal M of drive unit DU--Il As previously discussed, when a signal enters the drive unit through terminal M it is automatically operative to cause the drive unit to permit the opening of the associated gas regulating butterfly valves to the maximum amount, since under two-stove automatic operation one stove must supply the entire heat load when it is On Gas. Since stoves II and III in FIG. 4 are not On Gas, their drive units DU-II and DU-III are not operative.

FIG. 5 is similar to FIGS. 3 and 4 but shows the condition `of the circuitry when all three stoves are set for manual operation, one independently of the other, and while stove I is On Gas. Under these conditions, all three A/ M switches are in the manual position and a circuit is now complete from line LI through contacts N Zu of IRGI into terminal V of the drive unit. The manual setter can be manually set to any desired Value so as to produce from the drive unit an output proportional to the selected setting on the manual setter, to in turn cause a proportional amount of heat to be produced by stove I.

It is therefore seen by reference to FIGS. 3, 4 and 5 that as the system is set for a particular type of operation, whether three-stove fully automatic, two-stove fully automatic or manual, the circuitry shown in these figures is operative to automatically control and regulate the amount of heat to be produced by the stove or stoves, which are then On Gas.

This application is a continuation-impart of our application, Serial No. 852,370, iiled November l2, 1959, now United States Patent No. 3,034,775, assigned to the assignee of our present application.

While We have shown and described the preferred embodiments of our invention, it will be understood that the invention may be embodied otherwise than as herein specifrcally illustrated or described, `and that in the illustrated Aembodiment certain changes in the details of construction 23 and in the `form and arrangement of parts may be made without departing from the underlying idea or principles of this invention within the scope of the appended claims.

Having thus described our invention, what we claim `and desi-re to secured by Letters Patent is:

l. In a blast furnace installation having three hot blast stoves and adapted to be selectively operated either in a rst condition in which all three stoves are utilized and changed over automatically, in a second condition in which two of the three stoves are utilized and changed over automatically, or in a third condition in which each of the stoves is automatically operated independently of the others, and having means for producing an electrical output signal proportional to the required load for said blast furnace installation; the improvement comprising means for automatically distributing the heat load for providing the required blast furnace load among said stoves for each of said three conditions, said distributing means comprising an electrically operated gas volume regulator means for each stove, means electrically connecting said output signal to each of said gas volume regulating means, and means for automatically interrupting said electrical connecting means to each gas volune regulator means when said installation is not operating in said first condition, whereby t0 automatically transmit said output signal only when the installation is operating in said rst condition, for equally distributing said heat load among the stoves when the installation is operating in said first condition.

2. In a blast furnace installation having three hot blast stoves and adapted to be selectively operated either in a iirst condition in which all three stoves are utilized and changed over automatically, in a second condition in which two of the three stoves are utilized and changed over automatically, or in a third condition in which each of the stoves is automatically operated independently of the others, and having means for producing an electrical output signal proportional to the required load for said blast furnace installation; the improvement comprising means for automatically distributing the heat load for providing the required blast furnace load among said stoves for each of said three conditions, said distributing means comprising an electrically operated gas volume regulator means for each stove, means electrically connecting said output signal to each of said gas volume regulator means, means for automatically interrupting said electrical connecting means to each gas volume regulator means when said installation is not operating in said first condition, and means for automatically interrupting the electrical connecting means to the gas volume regulator means of a stove which is not being heated, whereby to automatically transmit said output signal only when the installation is operating in said lirst condition and only to the gas volume regulator means of a stove which is being heated, for equally distributing said heat load among the stoves that are being heated when the installation is operating in said first condition.

3. In a blast furnace installation having three hot blast stoves and adapted to be selectively operated either in a first condition in which all three stoves are utilized and changed over automatically, in a second condition in which two of the three stoves are utilized and changed over automatically, or in a third condition in which each of the stoves is automatically operated independently of the others, and having means for producing an electrical output signal proportional to the required load for said blast furnace installation; the improvement comprising means for automatically distributing the heat load for providing the required blast furnace load among said stoves for each of said three conditions, said distributing means comprising an electrically operated gas volume regulator means for each stove, each of said gas volume regulator means having a first and second electrical input terminal, the first of said terminals being operative, when an electrical signal is connected thereto, to cause the gas volume regulator to admit a volume of gas in the associated stove which is proportional to the ampliude of such connecting electrical signal, the second cf said terminals being operative, when an electrical signal is connected thereto, to cause the gas volume regulator to admit a fixed predeterminal volume of gas in the associated stove, means electrically connecting said output signal to said first terminal of each of said regulator means, and means for automatically interrupting said electrical connecting means to said first terminal of each regulator means when said installation is not operating in said first condition, whereby to automatically transmit said output signal only when the installation is operating in said first condition for equally distributing said heat load when the installation is in said first condition.

4. In a blast furnace installation having three hot blast stoves and adapted to be selectively operated either in a first condition in which all three stoves are utilized and changed over automatically, in a second condition in which two of the three stoves are utilized and changed over automatically, or in a third condition in which each of the stoves is automatically operated independently of the others, and having means for producing an electrical output signal proportional to the required load for said blast furnace installation; the improvement comprising means for automatically distributing the head load for providing the required blast furnace load among said stoves for each of said three conditions, said distributing means comprising an electrically operated gas volume regulator means for each stove, each of said gas volume regulator means having a first and second electrical input terminal, the first of said terminals being operative, when an electrical signal is connected thereto, to cause the gas volume regulator to admit a volume of gas in the associated stove, which is proportional to the amplitude of such connecting electrical signal, the second of said terminals being operative, when an electrical signal is connected thereto, to cause the gas volume regulator to admit a fixed predetermined volume of gas in the associated stove, means electrically connecting said output signal to said first terminal of each of said regulator' means, and means for automatically interrupting said electrical connecting means to said first terminal of each regulator means when said installation is not operating in said first condition, whereby to automatically transmit said output signal only when the installation is operating in said first condition for equally distributing said heat load when the installation is in said first condition, and means for automatically connecting an electrical signal to said second terminal of the regulator means of the two stoves which are in operation when said installation is operating in said second condition.

5. In a blast furnace installation having three hot blast stoves and adapted to be selectively operated either in a first condition in which all three stoves are utilized and changed over automatically, in a second condition in which two of the three stoves are utilized and changed over automatically, or in a third condition in which each of the stoves is automatically operated independently of the others, and having means for producing an electrical output signal proportional to the required load for said blast furnace installation; the improvement comprising means for automatically distributing the heat load for providing the required blast furnace load among said stoves for each of said three conditions, said distributing means comprising an electrically operated gas volume regulator means for each stove, each of said gas volume regulator means having a first and second electrical input terminal, the first of said terminals being operative, when an electrical signal is connected thereto, to cause the gas volume regulator to admit a volume of gas in the associated stove which is proportional to the amplitude of such connecting elec-trical signal, the second of said terminals being ope-rative, when an electrical signal is connected thereto, to cause the gas volume regnllator to admit a fixed lpredeterminal volume of gas in the associated stove, means electrically connecting said output signal to said first terminal of each of said regulator means, and means for automatically interrupting said electrical connecting means to said first terminal of each regulator means when said installation is not operating in said first condition, whereby to automatically transmit said output signal only when the installation is operating in said first condition for equally distributing said heat load when the installation is in said first condition, and means for automatically connecting a manually adjustable electrical signal to the rst terminal of the regulator means of each stove only when said installation is operated in said third condition.

6. In a blast furnace installation having three hot blast stoves and adapted to be selectively operated either in a first condition in which all three stoves are utilized and changed over automatically, in a second condition in which two of the three stoves are utilized and changed over automatically, or in a third condition in which each of the stoves is automatically operated independently of the others, and having means for producing an electrical output signal proportional to the required load for said blast furnace installation; the improvement comprising means for automatically distributing the heat load for providing the required blast furnace load among said stoves for each of said three conditions, said distributing means comprising an electrically operated gas volume regulator means for each stove, each of said gas volume regulator means having a first and second electrical input terminal, the first of said terminals being operative, when an electrical signal is connected thereto, to cause the gas volume regulator to admit a volume of gas in the associated stove which is proportional to the amplitude of such connecting electrical signal, the second of said terminals being operative, when an electrical signal is connected thereto, to cause the gas volume regulator to admit a xed predetermined volume of gas in the associated stove, means electrically connecting said output signal to said first terminal of each of said regulator means, and means for automatically interrupting said electrical connecting means to said first terminal of each regulator means when said installation is not operating in said first condition, whereby to automatically transmit said output signal only when the installation is operating in said first condition for equally distributing said heat load when the installation is in said first condition, means for automatically connecting an electrical signal to said second terminal of the regulator means of the two stoves which are in operation when said installation is operating in said second condition, and means for automatically connecting a manually adjustable electrical signal to the first terminal of the regulator means of each stove only when said installation is operated in said third condition.

7. In a blast furnace installation having three hot blast stoves and adapted to be selectively operated either in a first condition in which all three stoves are utilized and changed over automatically, in a second condition in which two of the three stoves are utilized and changed over automatically, or in a third condition in which each of the stoves is automatically operated independently of the others, and having means for producing an electrical output signal proportional to the required load for said blast furnace installation; the improvement comprising means for automatically distributing the heat load for providing the required blast furnace load among said stoves for each of said three conditions, said distributing means comprising an electrically operated gas volume regulator means for each sto-ve, each of said gas volume regulator means having a first and second electrical input terminal, the first of said terminals being operative, when an electrical signal is connected thereto, to cause the gas volume regulator to admit a volume of gas in the associated stove which is proportional to the amplitude of such connecting electrical signal, the second of said terminals being operative, When an electrical signal is connected thereto, to cause the gas volume regulator to admit a fixed predetermined volume of gas in the associated stove, means electrically connecting said output signal to said first terminal of each of said regulator means, and means for automatically interrupting said electrical connecting means to said iirst terminal of each regulator means when said installation is not operating in said rst condition, whereby to automatically transmit said output signal only when the installation is operating in said lirst condition for equally distributing said heat load when the installation is in said irst condition, and means for automatically interrupting the circuit to the rst and second terminal of the regulator means of any stove unless the latter is being heated.

8. In a blast furnace installation having three hot blast sto-ves and adapted to be selectively operated either in a first condition in which all three stoves are utilized and changed over automatically, in a second condition in which two of the three stoves are utilized and changed over automatically, or in a third condition in which each of the stoves is automatically operated independently of the others, and having means for producing an electrical output signal proportional to the required load for said blast furnace installation; the improvement comprising means for automatically distributing the heat load for providing the required blast furnace load among said stoves `for each of said three conditions, said distributing means comprising an electrically operated gas volume regulator means for each stove, each of said gas volume regulator means having a first and second electrical input terminal, the rst of said terminals being inoperative,

when an electrical signal is connected thereto, to cause the gas volume regulator to admit a volume of gas in the associated stove -which is proportional to the amplitude of such connecting electrical signal, the second of said terminals being operative, when an electrical signal is connected thereto, to cause the gas volume regulator to admit a liXed predetermined volume of gas in the associated stove, means electrically connecting said output signal to said first terminal of each of said regulator means, and means for automatically interrupting said electrical connecting means to said first terminal of each regulator means when said installation is not operating in said first condition, whereby to automatically transmit said output signal only when the installation is operating in said first condition for equally distributing said heat load when the installation is in said first condition, means for automatically connecting an electrical signal to said second terminal of the regulator means of the two stoves which are in operation when said installation is operating in said second condition, and means for automatically connecting a manually adjustable electrical signal to `the tirst terminal of the regulator means of each stove only when said installation is operated in said third condition, and means for automatically interrupting the circuit to the rst and second terminal of the regulator means of any stove unless the latter is being heated.

References Cited in the file of this patent UNTED STATES PATENTS 

